A comparative study between a small dose of ketamine, lidocaine 1%, and acetominophen infusion to decrease propofol injection pain

Background and objectivesPain during the injection of propofol is one of its drawbacks. The aim of this prospective, randomized and double-blinded study was to compare ketamine (K), lidocaine (L) 1%, and paracetamol (P) infusion as pretreatment before propofol injection regarding pain during injection.Patients and methodsA total of 200 patients aged between 20 and 60 years, ASA I or II physical status, were randomly assigned into four equal groups. All patients received pretreatment solutions made up in 20-ml syringes with isotonic saline 0.9%. All the patients were pretreated over a period of 20 s. In group K, patients received ketamine 0.5 mg/kg. In group L, patients received lidocaine 0.5 mg/kg. In group P, patients received paracetamol (perfagan 10 mg/ml) 2 mg/kg. In group C (which served as a control group), patients received isotonic saline. We placed a rubber tourniquet on the forearm for 50 s to occlude the venous blood before giving the study drug. A blinded researcher assessed the patient's pain on propofol injection using a four-point scale, hemodynamics, the incidence of complications, and the dose of propofol used to induce anesthesia.ResultsThere was a significant increase in the pain in group L compared with group K and group P. Also, there was a significant increase in the pain in group C compared with all other groups. After propofol injection, there was a significant decrease in the mean arterial pressure in P, L, and C groups in comparison with the baseline values. There was a significant decrease in the propofol dose for the induction of anesthesia in the ketamine group in comparison with the other groups.ConclusionPretreatment with paracetamol 2 mg/kg, ketamine 0.5 mg/kg, and lidocaine 0.5 mg/kg were significantly effective in attenuating the pain of propofol. However, pretreatment with lidocaine 0.5 mg/kg was the least effective and pretreatment with paracetamol 2 mg/kg was the most effective in attenuating propofol pain. The incidence of complications was not significant in all groups.